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The Contribution of Scientific Research to the 
Development of the Portland Cement 
Industry in the United States 


By Durr A. ABRAMS 


Professor in Charge, Structural Materials Research Laboratory, Lewis Institute, Chicago 


HISTORICAL ~ 
CENTURY ago, Joseph Aspdin, 


an obscure mason of Leeds,! Eng- 
land, was granted a patent by Kiyg 
George IV on an artificial stone which 
he called “Portland”? cement, because 
of its resemblance to the well-known 
building stone quarried on the Isle of 
Portland,—the stone of which West- 
minster Abbey was constructed. 
According to the fragmentary his- 
tory of Joseph Aspdin, his patent fol- 
lowed years of experimenting, so that 
the present cement industry, which has 
developed from Aspdin’s factory of 
1825, was founded upon research. His 
plan of combining two powdered raw 
materials in certain proportions, burn- 
ing them and then pulverizing the re- 
sulting clinker produced a cement 
much superior to the older hydraulic 
cements which were made from a single 
material that was lightly burned and 
then ground. The industry’s surpris- 
ing growth since Aspdin’s time has 
been based largely on that same factor; 
today scientific research into the con- 
stitution and manufacture of Portland 
cement and its use in making concrete 
is going forward on a still more exten- 
sive scale. 


PoRTLAND CEMENT IN THE U. S. 


The Portland cement industry in 


this country dates from 1872, when 


1The writer was present at the Town Hall 
Leeds, England, September, 1924, upon the oc- 
casion of the unveiling of a table in memory of 
Aspdin, at the joint centennial celebration of the 
discovery of Portland cement, held by British and 
American cement manufacturers. 


1 


David O. Saylor made the first cement 
of this type in eastern Pennsylvania. 
Here again success followed a period of 
experimenting, and while the equip- 
ment was crude, the work was based 
upon sound ideas. It was not practi- 
cal for the American manufacturers to 
draw extensively upon the store of in- 
formation then existing in Europe, and 
for many years development was slow. 
When a marked stimulus did come, it 
was through the introduction of new 
types of kilns and grinding mills which, 
particularly in the case of the kilns, 
followed a long period of often disap- 
pointing research. 

Through further investigation, it was 
discovered how to utilize pulverized 


‘coal in burning the clinker, in place of 


the more expensive and less widely 
distributed petroleum. Natural ce- 
ments have been made in the United 
States since the construction of the Erie 
Canal in 1820. In 1890, the produc- 
tion of natural cement was over 7,000,- 
000 barrels, in comparison with a third 
of a million barrels of Portland cement. 
In 1900 the country’s output of Port- 
land cement exceeded that of the older 
natural cement for the first time. 

There are now 134 operating Port- 
land cement plants in this country, lo- 
cated in 29 states scattered from the 
Atlantic coast to the Pacific, and from 
the Canadian border to Mexico. The 
latest figures available from the U. 8. 
Geological Survey show an output of 
nearly 150,000,000 barrels for 1924. 

A better product, discovered and de- 
veloped through research, has strongly 
entrenched itself, while the once firmly 


aa Tur ANNALS OF THE AMERICAN ACADEMY 


established natural cement has _ al- 
most disappeared from the market. 
Some writers have attributed the de- 
cline of the natural cement industry to 
the lack of an aggressive educational 
and promotional policy, based upon re- 
search, as much as to anything else. 


COMPETITION WITH FoREIGN CEMENTS 


An understanding of present condi- 
tions in the Portland cement industry 
and the part research has played in its 
development will be best secured by 
going back some three decades. In 
1895 the domestic Portland cement 
industry, then 23 years old, was pro- 
ducing less than 1,000,000 barrels a 
year, whereas imports were about 
3,000,000 barrels. ‘T'wo years later the 
United States production had grown to 
2,700,000 barrels, which for the first 
time was greater than imports. ‘Three 
years later the annual output had more 
than tripled, and by 1902 had reached 
more than 17,000,000 barrels. 


MANUFACTURE OF PoRTLAND CEMENT 


The manufacture of cement is fairly 
complicated because of the large quan- 
tities of materials that must be han- 
dled, and the close control of the ingre- 
dients that must be maintained at all 
times. The essential constituents of 
cement are lime, silica and alumina. 
These ingredients may be secured from 
a number of sources, the most common 
of which are limestone, marl and oyster 
shells for the lime; and clay, shale and 
blast furnace slag for the clayey mate- 
rials. In the case of blast furnace slag, 
considerable lime is also secured. 

Scientific research has made possible 
the utilization of deposits which once 
would have been considered unsatis- 
factory and has extended the possible 
locations of plants with a resulting 
saving to users of cement in various 
localities. Since cement is such a 
heavy, low-priced commodity, freight 


rates make up an important part of the 
cost where the shipping distance is 
considerable. 

The raw materials are quarried or 
excavated by powerful machinery and 
taken to the plant usually in cars. 
There the rock is put through crushers 
followed by various types of grinding 
apparatus until a materia] finer than 
flour is secured. Following crushing, 
the materials are weighed out in pro- 
portions determined by the chemist’s 
frequent tests so that in grinding a very 
intimate mixture of the ingredients is 
secured. 

The finely pulverized “‘raw mix”’ is 
now ready for the kilns, which are 
great steel cylinders, 6 to 10 feet in 
diameter and 100 to 250 feet long, lined 
with firebrick. The mixture is fed into 
one end of the kiln, which is slightly 
higher than the other so that as the 
kiln rotates the material slowly passes 
toward the lower end. The pulverized 
coal, fuel oil, or gas is blown into the 
lower end and burns in a great tongue 
of flame 30 to 40 feet in length, pro- 
ducing a heat greater than that re- 
quired to melt steel. It is in this high- 
temperature zone that entirely new 
physical and chemical compounds are 
formed, called cement clinker. ‘This is 
white-hot as it leaves the kiln, but upon 
emerging from rotary coolers it is ready 
for the storage pile or for the grinding 
mills. | 

Clinker, which consists of particles 
ranging from the size of a pea to that of 
a walnut, is glass-hard and is not 
affected by weather and needs only to 
be finely pulverized to produce cement. 
A little gypsum is added to control the 
rate of hardening of the cement. 

Although a variety of machinery is 
utilized in grinding clinker, final grind- 
ing is commonly done in rotating steel 
cylinders partly filled with a charge of 
many tons of small steel balls. As the 
cylinder rotates, these balls are carried 


Screntiric Resfarch AND THE Porttanp CEMENT INDUSTRY 3 


part way up the side and then are 
thrown outward and down, resulting in 
pulverization of the clinker. 


PROPERTIES OF PoRTLAND CEMENT 


No matter what raw materials are 
utilized, the resulting cement must 
have certain well-defined characteris- 
tics and must meet standard specifica- 
tions which have been adopted jointly 
by the American Society for Testing 
- Materials and the U. S. Government. 
The standard specifications require 
that at least 78 per cent of the finished 
cement be fine enough to shake through 
a sieve having 40,000 holes to the square 
inch. This sieve is made from bronze 
wire, but is woven much more finely 
than a silk handkerchief. 

At the present time the quality stand- 
ards of the cement industry are well 
established and all cement must meet 
these specifications. In the early days 
_ of the industry, a great deal of atten- 
tion was paid to securing a product that 
would equal or exceed the imported 
brands and careful investigation was 
absolutely necessary in order to de- 
velop methods of quality control. In 
fact, it was only after the quality of the 
domestic product had been fully dem- 
onstrated that engineers adopted it. 
Without research the industry would 
never have reached a firm basis for its 
extensive later growth. 


Quatity CONTROL IN CEMENT PLANTS 


Chemical and physical laboratories 
are essential parts of every cement 
plant, and are jointly responsible for 
the control of the quality of the cement. 
. The first tests of the chemist are made 

on samples secured from the drill holes 
in the quarry, so that he knows what 
to expect from different parts of the 
quarry after the material is blasted 
loose. This control continues through 
the manufacturing process. It is the 
chemist’s duty to set and lock the scales 


which govern the proportioning of the 
raw materials, and to change the set- 
ting as the materials change. 

The physical laboratory makes tests 
during the process of manufacture, but 
it is concerned chiefly with testing the 
finished cement to see that it conforms 
to the standard specifications. 


Raw MarTeriAts IN CEMENT 


Perhaps some idea may be given by 
the following facts as to what it means 
for an industry to take some 48,000,000 
tons of raw materials in the course of a 
year, put it through varied manufac- 
turing processes involving more than 


80 operations and from it secure 28,- 


000,000 tons of finished cement. It is 
estimated that 11,000,000 tons of coal 
were burned during the year, in addi- 
tion to large quantities of fuel oil and 
gas. In fact, the Portland cement in- . 
dustry is the fourth largest manufac- 
turing user of coal and the largest user 
of pulverized coal. 

_ Again, in breaking up the rock re- 
quired as raw material, more than 
17,000,000 pounds of explosives were 
set off in cement mill quarries during 
1924. 

Cement is shipped chiefly in return- 
able cloth sacks, four to the barrel. 
To replace the sacks lost and worn out 
in one year, a strip of cloth more than 
37,000 miles long and 30 inches wide 
was needed. In addition to this, 
50,000,000 heavy paper bags were used 
during the year. The most recent 
figures available from the Interstate 
Commerce Commission place the ce- 
ment industry fourth among shippers 
of manufactured articles. 


PoRTLAND CEMENT ASSOCIATION 


Here then was a rapidly developing 
industry, until a few. years previous 
greatly handicapped by a marked 
preference on the part of the users for 


A Tur ANNALS OF THE AMERICAN ACADEMY 


the product of foreign competitors, but 
fortified with recent improvements in 
manufacturing methods that had made 
the rapid expansion possible. Yet the 
industry was without any well-devel- 
oped plan or means of broadening its 
field of usefulness. In fact, many 
puzzling questions were before the 
manufacturers, and accordingly in 1902 
a meeting of the producers in the east- 
ern states, where more than half of the 
entire output was then made, was held 
in New York for a discussion of matters 
of interest. This first meeting was 
devoted largely to the troublesome 
question of containers for the product, 
but it opened up such possibilities of 
co-operative effort in solving common 
problems of manufacturing and market 
development that before adjourn- 
ment a permanent organization was 
formed. 

Within a year other manufacturers 
from the West had joined and national 
representation was secured. ‘That or- 
ganization is still in existence as the 
Portland Cement Association, which 
has as members nearly 90 per cent of 
the companies manufacturing Portland 
cement in the United States, and in 
addition, several companies operating 
plants in Canada, Mexico, Cuba and 
South America. 

The one paid secretary of the first 
organization has now been replaced 
by some 425 employes of the pres- 
ent Association. Jn order that Asso- 
ciation activities might be carried on 
with great efficiency and in the light 
of local conditions, 28 district offices 
have been established in all parts of the 
United States, and one in Western 
Canada. General headquarters are 
maintained in Chicago, where there is 
also a research laboratory maintained 
jointly by the Portland Cement Asso- 
ciation and the Lewis Institute under 
the name of the Structural Materials 
Research Laboratory. 


An EpucATIONAL PROGRAM 


In effect, the Portland Cement Asso- 
ciation is the educational-promotional- 
research foundation of the cement 
industry. It is not engaged in the man- 
ufacture or sale of cement, but carries on 
for the entire industry educational 
and promotional work “to improve and 
extend the use of concrete,”’ all of which 
is based upon facts established by pains- 
taking research within the industry 
and by other organizations such as the 
U.S. Bureau of Standards and various 
university laboratories. 

The Association is a “Service’’ or- 
ganization for the user of cement as 
well as for the manufacturer. Princi- 
pal attention is given the educational 
and promotional work which has as its 
objective the extension of the use of 
cement. A secondary field of endeavor 
is the increased efficiency in manufac- 
turing methods. 


CoNCRETE RESEARCH 


In considering the major field of the 
Association’s activity, that devoted to 
extending the use of concrete, the 
leaders early saw that increasing the 
use of cement through education and 
promotion presented some peculiar 
problems. Cement is practically never 
used alone, but is mixed with other ma- 
terials such as sand and stone in making 
concrete and mortar. Because of the 
ease of transforming these various 
materials into concrete, a great number 
of people—some of them with very 
little practical knowledge of construc- 
tion—soon began to make things of 
concrete. 

Contrary to earlier accepted views, 
the way in which concrete is made has 
a great deal to do with the service it 
will give. ‘Therefore, no matter how 
careful the manufacturers were in turn- 
ing out a cement, it quite frequently 
happened that their product would be 


ScrENTIFIC RESEARCH AND THE PortTLAND CEMENT INDUSTRY 5 


incorrectly used and consequently dis- 
satisfaction resulted which might 
strongly influence the builder and 
others against future use of concrete. 
The amount of mixing water added to 
the cement and aggregates—the sand 
and stone—in making concrete, the 
thoroughness of mixing, and the curing 
of the concrete, are some of the factors 
that govern the strength and quality of 
the final structure. 

Realizing that the knowledge of 
concrete making had not kept pace 
with the development of cement mak- 
ing, the manufacturers recognized that 
the biggest problem before them was 
the education of the user in the best 
ways of making concrete. 

In order that they might tell the user 
these important facts about concrete, 
the Association leaders knew that they 
must be sure of the basic principles and 
that led to one of the most important 
factors in the success of the Associa- 
tion’s work, namely, the establishment 
of a department primarily for research 
on concrete. 

Of course, a great deal of valuable 
investigation in that field had already 
been carried on. Many governmental 
bureaus, university laboratories, and 
others had conducted investigations; 
the difficulty was that the results 
lacked co-ordination, and in many 
instances were conflicting. 


STRUCTURAL MATERIALS RESEARCH 
LABORATORY 


In 1916, the Portland Cement Asso- 
ciation joined with Lewis Institute, a 
polytechnic school in Chicago, in es- 
_tablishing the Structural Materials 
Research Laboratory, where research 
into matters pertaining to concrete 
making had already been under way for 
about two years. 

Only eight members made up the 
staff at the time the co-operative work 
was begun, and the contribution of the 


Cement Association during the first 
year was about $15,000. 

From the first, the value of this work 
was recognized, although it was four 
years before the first bulletin describing 
the results of some of the investigation- 
al work was issued. The Laboratory 
developed steadily and additions were 
made from time to time both to equip- 
ment and personnel. Space on three 
floors is now required, and a staff of 
about 40 is employed by the Labora- 
tory. Tests are being made at the rate 
of about 45,000 per year. 

Inevitably more problems in such a 
broad field as concrete construction 
would present themselves for consider- 
ation than could be given adequate 
attention. Therefore, the selection of 
the problems to be investigated has re- 
ceived most careful consideration. An 
Advisory Committee, consisting of 
representatives of Lewis Institute and > 
the Portland Cement Association, de- 
termine the general policy and program 
of work for the Laboratory. Attention 
is focused upon one group of problems 
until satisfactory results have been 
secured, rather than dissipating the 
energies of the staff on unco-ordinated 
minor problems. 


FUNDAMENTAL PRINCIPLES OF 
CONCRETE 


The first important work of the Lab- 
oratory was to establish definitely the 
vital part that the water content of the 
mixture plays in determining the 
strength of concrete. It was found that 
the use of a pint too much mixing water 
in a batch of concrete was equivalent in 
its weakening effect to leaving out 
two pounds of cement. Therefore, 
this matter of maintaining a uniform 
and desirable consistency is extremely 
important. 

Important studies have been carried 
out which gave a better understanding 
of the effect of size and grading of ag- 


6 Tur ANNALS OF THE AMERICAN ACADEMY 


gregate, the changes in quality of con- 
crete resulting from variations in ce- 
ment content, effect of different foreign 
materials in concrete, and many other 
factors. 


Co-OPERATION WITH OTHER 
- ORGANIZATIONS 


Much has been done in co-operation 
with other testing laboratories and 
technical societies, such as the Ameri- 
can Society for Testing Materials, the 
American Concrete Institute, the Bu- 
reau of Standards, the Bureau of Public 
Roads, the Associated General Con- 
tractors, and the California Highway 
Commission. 

Dissemination of the findings is 
given as complete attention as the in- 
vestigational work itself; until this in- 
formation is in the hands of the user of 
concrete, it has failed to accomplish the 
purpose of the cement industry in se- 
curing it. These results are frequently 
first given in papers before technical 
societies; later these papers are dis- 
tributed in printed form. Other data 
are issued directly by the Laboratory 
as bulletins and circulars. 

Facts from the Laboratory are given 
prominence in the literature of the Asso- 
ciation and in some instances form the 
entire basis of the publication. Through 
articles in the leading technical jour- 
nals, prepared both by the Laboratory 
and the Association, the facts are kept 
before those most interested. 


CoNCRETE Roaps 


One or two instances will show what 
this research has meant to the users of 
concrete, and consequently to the 
cement industry, through the broaden- 
ing of the market for its product be- 
cause of the satisfaction and economy 
secured through the proper use of 
cement. 

The concrete road is a comparatively 
modern development. As with any- 


thing new, the first examples left much 
to be desired. It was only through 
careful study and research into better 
methods of building concrete pave- 
ments—first on the part of individual 
cement companies and later on the part 
of the Portland Cement Association 
engineers in co-operation with this 
Laboratory, all of whom worked with 
the governmental agencies most inter- 
ested—that modern methods of high- 
way construction have been developed. 
In the five-year period, 1909 to 1913, 
which comprises the early days of con- 
crete roads, less than 114 per cent of 
the cement produced in the United 
States was used in pavements. In the 
five-year period, 1920 to 1924, this was 
increased to nearly 20 percent. Atthe 
present time, about 25 per cent of the 
cement made is being used in pave- 
ments of various classes. 


CONCRETE AGGREGATES 


In some parts of the country, it has 
been difficult to secure satisfactory 
aggregates at a reasonable cost for use 
in building concrete highways. In one 
instance in a western state, it was nec- 
essary to open a quarry and set up a 
crushing plant near the job. But the 
rock was of such a nature that crushing 
produced too much of the smaller 
pieces. In making concrete in accord- 
ance with the usually accepted specifi- 
cations it was necessary to throw away 
more than one-third of this crushed 
rock. 

One of the fieldmen of the Associa- 
tion suggested to the engineers in 
charge that the Laboratory might find 
means of utilizing some of the wasted 
material. Accordingly, the problem 
was submitted to the Laboratory with 
samples of the crushed rock. These 
samples were carefully examined and 
the usual concrete tests made. To the 
results, we applied the systematized 
knowledge gained in thousands of 


ScIENTIFIC RESEARCH AND THE PorTLAND CEMENT INDUSTRY 7 


earlier tests and were able to recom- 
mend a mixture of fine and coarse ag- 
gregates so that nearly all the material 
could be utilized without sacrificing 
any of the strength of the resulting con- 
crete. These recommendations were 
put into effect; on this job alone the 
saving amounted to $30,000, or more 
than enough to build another mile of 
concrete road. 


ReEsEARCH APPLIED TO FIELD CONTROL 


There are always those who contend 
that the results of laboratory research 
may be theoretically correct, but are 
not practical in the field. But this ob- 
jection cannot be raised in this case, 
because many prominent engineers and 
contractors have applied the results on 
important jobs, and the principles an- 
nounced from time to time are now ac- 
cepted by the construction world. 

One interesting example of the appli- 
cation of laboratory principles to con- 
crete construction is found in the bridge 
built by the Big Four Railroad over the 
Miami River at Sidney, Ohio. T'wenty- 
eight thousand cubic yards of concrete 
went into this bridge, all of which was 
placed under scientific control. In- 
stead of using arbitrary proportions of 
the aggregates, guessing at the consis- 
tency of the concrete, and trusting to 
luck for curing, the mixture was de- 
signed for the desired strength on the 
basis of the aggregates used. ‘Tests 
were frequently made to control the 
consistency and modern methods of 
curing were employed. 

This research is not confined to the 
laboratory. Whenever desirable, tests 
‘have actually been made on the job in 
studying the efficiency of various field 
methods. During 1923, important 
field investigations were made in the 
vicinity of New York City and Phila- 
delphia during the construction of 
seven large reinforced concrete build- 
ings. ‘These tests were made for the 


purpose of determining the uniformity 
of concrete under job conditions by the 
usual methods of proportioning an 
control. 

In 1924, tests on curing of concrete 
roads were carried out in California in| 
co-operation with the State Highway 
Commission. 


CONSERVATION OF POWER 


Through the Portland Cement Asso- 
ciation it has been possible for the 
manufacturers to co-operate in effective 
research into many subjects involved in 
the making of cement. This work has 
been carried on chiefly through a Con- 
servation Engineer working under the 
direction of a Committee on Conserva- 
tion, the membership of which in- 
cludes representative cement company 
officials. 

An outstanding example of this re- 
search is found in the utilization of the 
hot gases from the kiln in generating 
steam for power. Because of the high 
temperature (2,500° to 3,000° Fahren- 
heit) required near the lower end of the 
kiln in order that the raw mixture may 
be changed into cement clinker, the 


gases emerging from the kilnstaek have 


a temperature of 1,000° to /16,000° F. 
The volume of these hot gases_is-véry 
great, hence it has been found entirely 
practical to utilize them in heating 
boilers which generate from 50 per cent 
up to all of the steam required to furnish 
power for the plant. Since the power 
demands in cement making are ex- 
tremely heavy, this is an important 
matter. Of course, large expenditure is 
required for the installation of a “waste 
heat”’ system, but the eventual saving 
is considerable. The adoption of waste 
heat boilers has been rapid, and approx- 
imately 50 plants either have them in 
operation or in the course of installa- 
tion. 

Other matters recently investigated 
are the factors influencing the ease of 


8 Tur ANNALS OF THE AMERICAN ACADEMY 


grinding cement clinker and the effi- 
ciency of different grinding media, the 
fineness of grinding of the pulverized 
coal so widely used as fuel in the kilns, 
and the various types of refractories for 
lining kilns have also been studied. 


PREVENTION OF PLANT ACCIDENTS 


Through theco-operation of the Asso- 
ciation with the individual companies, 
the number of accidents in proportion 
to the man-hours worked in the plants 
has been much reduced. Statistics for 
1923 show a reduction of 17 per cent in 
accidents in the cement industry, 
whereas an increase occurred in acci- 
dents throughout industry in general. 


STUDIES OF CONSTITUTION OF 
PoRTLAND CEMENT 


At the present time a most thorough 
investigation into the constitution of 
Portland cement is being carried on in 
co-operation with the U. S. Bureau of 
Standards. Although methodsof man- 
ufacturing cement have been carefully 
worked out and considerable study 
given the chemistry involved, investi- 
gation has not thus far given positive 
information concerning the real con- 
stitution of Portland cement as dis- 


tinguished from its composition and has 
failed to explain the hardening process 
of the ground clinker. Here the latest 
developments in the chemical and 
physical sciences are being employed in 
a study of these obscure questions. 
While several years may be required to 
complete these investigations, it is 
anticipated that the work can be car- 
ried to a successful conclusion and will 
provide basic information of much 
value in the future development of the 
use of Portland cement as well as in its 
manufacture. 

No better grounds for the promotion 
of concrete for use in any particular 
structure can be found than the 
strength, economy, permanence, and 
satisfactory service of similar structures 
already in use. Such examples can be 
secured only if the ingredients of con- 
crete are good and, furthermore, if the 
concrete itself is properly designed, 
mixed and cured. The discovery of the 
basic principles underlying success in 
concrete making has called for exten- 
sive research, and it is only after the 
results of this research have been 
adopted that the foundation for the 
future success of the cement industry 
has been made more secure. 


e 


By 


